ObfuscationAttribute Class

Definition

Namespace:

System.Reflection

Assembly:

System.Runtime.dll

Source:

ObfuscationAttribute.cs

Instructs obfuscation tools to take the specified actions for an assembly, type, or member.

public ref class ObfuscationAttribute sealed : Attribute

[System.AttributeUsage(System.AttributeTargets.Assembly | System.AttributeTargets.Class | System.AttributeTargets.Delegate | System.AttributeTargets.Enum | System.AttributeTargets.Event | System.AttributeTargets.Field | System.AttributeTargets.Interface | System.AttributeTargets.Method | System.AttributeTargets.Parameter | System.AttributeTargets.Property | System.AttributeTargets.Struct, AllowMultiple=true, Inherited=false)]
public sealed class ObfuscationAttribute : Attribute

[<System.AttributeUsage(System.AttributeTargets.Assembly | System.AttributeTargets.Class | System.AttributeTargets.Delegate | System.AttributeTargets.Enum | System.AttributeTargets.Event | System.AttributeTargets.Field | System.AttributeTargets.Interface | System.AttributeTargets.Method | System.AttributeTargets.Parameter | System.AttributeTargets.Property | System.AttributeTargets.Struct, AllowMultiple=true, Inherited=false)>]
type ObfuscationAttribute = class
    inherit Attribute

Public NotInheritable Class ObfuscationAttribute
Inherits Attribute

Inheritance

Object

Attribute

ObfuscationAttribute

Attributes

AttributeUsageAttribute

Examples

The following code example shows a public assembly with two types: Type1 and Type2. The assembly is marked for obfuscation with the ObfuscateAssemblyAttribute, which marks the assembly to be treated as public (that is, the AssemblyIsPrivate property is false).

Type1 is marked for obfuscation because the assembly is marked for obfuscation. One member of Type1 is excluded from obfuscation, using the Exclude property.

Type2 is excluded from obfuscation, but its members are marked for obfuscation because the ApplyToMembers property is false.

The MethodA method of Type2 is marked with the value "default" for the Feature property. It is necessary to specify false for the Exclude property to avoid excluding MethodA from obfuscation, because the default for the Exclude property is true. The obfuscation tool should not strip the attribute after obfuscation because the StripAfterObfuscation property is false. All the other attributes in this code example are stripped after obfuscation, because the StripAfterObfuscation property is not specified, and therefore defaults to true.

The code example includes code to display the attributes and their properties. You can also examine the attributes by opening the DLL with the Ildasm.exe (IL Disassembler).

using System;
using System.Reflection;

// Mark this public assembly for obfuscation.
[assembly:ObfuscateAssemblyAttribute(false)]

// This class is marked for obfuscation, because the assembly
// is marked.
public class Type1
{

    // Exclude this method from obfuscation. The default value
    // of the Exclude property is true, so it is not necessary
    // to specify Exclude=True, although spelling it out makes
    // your intent clearer.
    [ObfuscationAttribute(Exclude=true)]
    public void MethodA() {}

    // This member is marked for obfuscation because the class
    // is marked.
    public void MethodB() {}
}

// Exclude this type from obfuscation, but do not apply that
// exclusion to members. The default value of the Exclude
// property is true, so it is not necessary to specify
// Exclude=true, although spelling it out makes your intent
// clearer.
[ObfuscationAttribute(Exclude=true, ApplyToMembers=false)]
public class Type2
{

    // The exclusion of the type is not applied to its members,
    // however in order to mark the member with the "default"
    // feature it is necessary to specify Exclude=false,
    // because the default value of Exclude is true. The tool
    // should not strip this attribute after obfuscation.
    [ObfuscationAttribute(Exclude=false, Feature="default",
        StripAfterObfuscation=false)]
    public void MethodA() {}

    // This member is marked for obfuscation, because the
    // exclusion of the type is not applied to its members.
    public void MethodB() {}
}

// This class only exists to provide an entry point for the
// assembly and to display the attribute values.
internal class Test
{

    public static void Main()
    {

        // Display the ObfuscateAssemblyAttribute properties
        // for the assembly.
        Assembly assem = typeof(Test).Assembly;
        object[] assemAttrs = assem.GetCustomAttributes(
            typeof(ObfuscateAssemblyAttribute), false);

        foreach( Attribute a in assemAttrs )
        {
            ShowObfuscateAssembly((ObfuscateAssemblyAttribute) a);
        }

        // Display the ObfuscationAttribute properties for each
        // type that is visible to users of the assembly.
        foreach( Type t in assem.GetTypes() )
        {
            if (t.IsVisible)
            {
                object[] tAttrs = t.GetCustomAttributes(
                    typeof(ObfuscationAttribute), false);

                foreach( Attribute a in tAttrs )
                {
                    ShowObfuscation(((ObfuscationAttribute) a),
                        t.Name);
                }

                // Display the ObfuscationAttribute properties
                // for each member in the type.
                foreach( MemberInfo m in t.GetMembers() )
                {
                    object[] mAttrs = m.GetCustomAttributes(
                        typeof(ObfuscationAttribute), false);

                    foreach( Attribute a in mAttrs )
                    {
                        ShowObfuscation(((ObfuscationAttribute) a),
                            t.Name + "." + m.Name);
                    }
                }
            }
        }
    }

    private static void ShowObfuscateAssembly(
        ObfuscateAssemblyAttribute ob)
    {
        Console.WriteLine("\r\nObfuscateAssemblyAttribute properties:");
        Console.WriteLine("   AssemblyIsPrivate: {0}",
            ob.AssemblyIsPrivate);
        Console.WriteLine("   StripAfterObfuscation: {0}",
            ob.StripAfterObfuscation);
    }

    private static void ShowObfuscation(
        ObfuscationAttribute ob, string target)
    {
        Console.WriteLine("\r\nObfuscationAttribute properties for: {0}",
            target);
        Console.WriteLine("   Exclude: {0}", ob.Exclude);
        Console.WriteLine("   Feature: {0}", ob.Feature);
        Console.WriteLine("   StripAfterObfuscation: {0}",
            ob.StripAfterObfuscation);
        Console.WriteLine("   ApplyToMembers: {0}", ob.ApplyToMembers);
    }
}

/* This code example produces the following output:

ObfuscateAssemblyAttribute properties:
   AssemblyIsPrivate: False
   StripAfterObfuscation: True

ObfuscationAttribute properties for: Type1.MethodA
   Exclude: True
   Feature: all
   StripAfterObfuscation: True
   ApplyToMembers: True

ObfuscationAttribute properties for: Type2
   Exclude: True
   Feature: all
   StripAfterObfuscation: True
   ApplyToMembers: False

ObfuscationAttribute properties for: Type2.MethodA
   Exclude: False
   Feature: default
   StripAfterObfuscation: False
   ApplyToMembers: True
 */

Imports System.Reflection

' Mark this public assembly for obfuscation.
<Assembly: ObfuscateAssemblyAttribute(False)>

' This class is marked for obfuscation, because the assembly
' is marked.
Public Class Type1

    ' Exclude this method from obfuscation. The default value
    ' of the Exclude property is True, so it is not necessary
    ' to specify Exclude:=True, although spelling it out makes
    ' your intent clearer.
    <ObfuscationAttribute(Exclude:=True)> _
    Public Sub MethodA()
    End Sub

    ' This member is marked for obfuscation because the class
    ' is marked.
    Public Sub MethodB()
    End Sub

End Class

' Exclude this type from obfuscation, but do not apply that
' exclusion to members. The default value of the Exclude 
' property is True, so it is not necessary to specify 
' Exclude:=True, although spelling it out makes your intent 
' clearer.
<ObfuscationAttribute(Exclude:=True, ApplyToMembers:=False)> _
Public Class Type2

    ' The exclusion of the type is not applied to its members,
    ' however in order to mark the member with the "default" 
    ' feature it is necessary to specify Exclude:=False,
    ' because the default value of Exclude is True. The tool
    ' should not strip this attribute after obfuscation.
    <ObfuscationAttribute(Exclude:=False, _
        Feature:="default", StripAfterObfuscation:=False)> _
    Public Sub MethodA()
    End Sub

    ' This member is marked for obfuscation, because the 
    ' exclusion of the type is not applied to its members.
    Public Sub MethodB()
    End Sub

End Class

' This class only exists to provide an entry point for the
' assembly and to display the attribute values.
Friend Class Test

    Public Shared Sub Main()

        ' Display the ObfuscateAssemblyAttribute properties
        ' for the assembly.        
        Dim assem As Assembly =GetType(Test).Assembly
        Dim assemAttrs() As Object = _
            assem.GetCustomAttributes( _
                GetType(ObfuscateAssemblyAttribute), _
                False)

        For Each a As Attribute In assemAttrs
            ShowObfuscateAssembly(CType(a, ObfuscateAssemblyAttribute))
        Next

        ' Display the ObfuscationAttribute properties for each
        ' type that is visible to users of the assembly.
        For Each t As Type In assem.GetTypes()
            If t.IsVisible Then
                Dim tAttrs() As Object = _
                    t.GetCustomAttributes( _
                        GetType(ObfuscationAttribute), _
                        False)

                For Each a As Attribute In tAttrs
                    ShowObfuscation(CType(a, ObfuscationAttribute), _
                        t.Name)
                Next

                ' Display the ObfuscationAttribute properties
                ' for each member in the type.
                For Each m As MemberInfo In t.GetMembers()
                    Dim mAttrs() As Object = _
                        m.GetCustomAttributes( _
                            GetType(ObfuscationAttribute), _
                            False)

                    For Each a As Attribute In mAttrs
                        ShowObfuscation(CType(a, ObfuscationAttribute), _
                            t.Name & "." & m.Name)
                    Next
                Next
            End If
        Next
    End Sub

    Private Shared Sub ShowObfuscateAssembly( _
        ByVal ob As ObfuscateAssemblyAttribute)
        
        Console.WriteLine(vbCrLf & "ObfuscateAssemblyAttribute properties:")
        Console.WriteLine("   AssemblyIsPrivate: " _
            & ob.AssemblyIsPrivate)
        Console.WriteLine("   StripAfterObfuscation: " _
            & ob.StripAfterObfuscation)

    End Sub

    Private Shared Sub ShowObfuscation( _
        ByVal ob As ObfuscationAttribute, _
        ByVal target As String)
        
        Console.WriteLine(vbCrLf _
            & "ObfuscationAttribute properties for: " _
            & target)
        Console.WriteLine("   Exclude: " & ob.Exclude)
        Console.WriteLine("   Feature: " & ob.Feature)
        Console.WriteLine("   StripAfterObfuscation: " _
            & ob.StripAfterObfuscation)
        Console.WriteLine("   ApplyToMembers: " & ob.ApplyToMembers)

    End Sub
End Class

' This code example produces the following output:
'
'ObfuscateAssemblyAttribute properties:
'   AssemblyIsPrivate: False
'   StripAfterObfuscation: True
'
'ObfuscationAttribute properties for: Type1.MethodA
'   Exclude: True
'   Feature: all
'   StripAfterObfuscation: True
'   ApplyToMembers: True
'
'ObfuscationAttribute properties for: Type2
'   Exclude: True
'   Feature: all
'   StripAfterObfuscation: True
'   ApplyToMembers: False
'
'ObfuscationAttribute properties for: Type2.MethodA
'   Exclude: False
'   Feature: default
'   StripAfterObfuscation: False
'   ApplyToMembers: True

Remarks

The ObfuscationAttribute and ObfuscateAssemblyAttribute attributes allow assembly authors to annotate their binaries so that obfuscation tools can process them correctly with minimal external configuration.

Important

Applying this attribute does not automatically obfuscate the code entity to which you apply it. Applying the attribute is an alternative to creating a configuration file for the obfuscation tool. That is, it merely provides instructions for an obfuscation tool. Microsoft recommends that vendors of obfuscation tools follow the semantics described here. However, there is no guarantee that a particular tool follows Microsoft recommendations.

The ObfuscationAttribute attribute has a string Feature property. Obfuscation tools can map the string values of this property to features they implement, preferably by using an XML configuration file that users can access. The ObfuscationAttribute defines two feature strings, "default" and "all". The string "default" should map to the default obfuscation features of a tool, and "all" should map to the complete set of obfuscation features supported by a tool. The default value of the Feature property is "all", enabling the complete set of obfuscation features.

When applied to an assembly, ObfuscationAttribute also applies to all types within the assembly. If the ApplyToMembers property is not specified, or is set to true, the attribute applies to all members as well. ObfuscationAttribute does not specify whether an assembly is public or private. To specify whether an assembly is public or private, use the ObfuscateAssemblyAttribute attribute.

When applied to classes and structures, ObfuscationAttribute also applies to all members of the type if the ApplyToMembers property is not specified, or is set to true.

When applied to methods, parameters, fields, and properties, the attribute affects only the entity to which it is applied.

Constructors

ObfuscationAttribute()

Initializes a new instance of the ObfuscationAttribute class.

Properties

ApplyToMembers	Gets or sets a Boolean value indicating whether the attribute of a type is to apply to the members of the type.
Exclude	Gets or sets a Boolean value indicating whether the obfuscation tool should exclude the type or member from obfuscation.
Feature	Gets or sets a string value that is recognized by the obfuscation tool, and which specifies processing options.
StripAfterObfuscation	Gets or sets a Boolean value indicating whether the obfuscation tool should remove this attribute after processing.
TypeId	When implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute)

Methods

Equals(Object)	Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute)
GetHashCode()	Returns the hash code for this instance. (Inherited from Attribute)
GetType()	Gets the Type of the current instance. (Inherited from Object)
IsDefaultAttribute()	When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute)
Match(Object)	When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
ToString()	Returns a string that represents the current object. (Inherited from Object)

See also

• ObfuscateAssemblyAttribute